Skin testing device



FIG. 1 is a top front perspective view of a skin testing device showing our new design;

FIG. 2 is a top left perspective view thereof; and,

FIG. 3 is a top front perspective view thereof.

The broken lines showing portions of a skin testing device is included for the purpose of illustrating environmental structure and forms no part of the claimed design. 

The ornamental design for a skin testing device, as shown and described. 